Portable lighting devices

ABSTRACT

A flashlight having a locking mechanism for securing a head skirt to a head assembly is disclosed. A circuit for temporarily remember the mode of operation of the flashlight is also disclosed.

TECHNICAL FIELD

The present invention relates to portable lighting devices, includingfor example, flashlights and headlamps, and their circuitry.

BACKGROUND

Various hand held or portable lighting devices, including flashlights,are known in the art. Flashlights typically include one or more dry cellbatteries having positive and negative electrodes. In certainflashlights, the batteries are arranged in series in a batterycompartment of a barrel or housing that can be used to hold theflashlights. An electrical circuit is frequently established from abattery electrode through conductive means which are electricallycoupled with an electrode of a light source, such as a lamp bulb or alight emitting diode (“LED”). After passing through the light source,the electric circuit continues through a second electrode of the lightsource in electrical contact with conductive means, which in turn are inelectrical contact with the other electrode of a battery. Typically, thecircuit includes a switch to open or close the circuit. Actuation of theswitch to close the electrical circuit enables current to pass throughthe lamp bulb, LED, or other light source—and through the filament, inthe case of an incandescent lamp bulb—thereby generating light.

Conventional flashlights also frequently include a head assembly, whichtypically includes a head, a lens, a face cap, and a reflector. The facecap in such flashlights is typically attached to the head to hold thelens and reflector relative to the head. Head assemblies of this typeare often threadably mounted to the forward end of the body or barrel ofthe flashlight via the head. Such head assemblies are not conducive,however, to accessing a light source alignment device, such as the lightsource alignment devices included in the flashlights described in U.S.Pat. No. 7,264,372 B2 (“the '372 patent) or U.S. Patent Publication2007/0064354 A1 (“the '354 publication”), both of which are assigned toMAG Instrument, Inc.

The '372 patent, teaches a head assembly including a face cap, lens, asleeve or skirt, and a sealing O-ring that are configured and arrangedso that the face cap and sleeve define a clearance envelope surroundingthe flange of a reflector module to solve this problem. As a result, thehead assembly may be rotated about the axis of the flashlight relativeto reflector module so as to cause the light source to translate alongthe axis of the reflector and vary the dispersion of light produced bythe flashlight. Further, the user may disengage the sleeve or skirt fromthe face cap and then slide it rearward to gain access to the lightsource alignment device and thereby move the light source in one or moredirections lateral to the axis of the reflector to align the substantialpoint source of light with the axis of the reflector. The disadvantageof this construction is that when the sleeve or skirt is disengaged fromthe face cap, the face cap, and hence the lens, are no longer connectedto the reflector module or any other portion of the flashlight, andhence they are liable to be dropped and/or damaged.

The flashlight described in the '354 publication solves this problemthrough the use of a support structure to which the face cap and skirt(which is referred to as the head in the '354 publication) areseparately attached. The face cap is threadably attached to the supportstructure of the flashlight and retains the lens and reflector relativeto the support structure. Thus, when the skirt is detached from thesupport structure to gain access to the light source alignment deviceincluded in the flashlight of the '354 publication, the face cap andassociated optics remain attached to the flashlight, thereby minimizingthe potential for damage to the same. However, the skirt of the '354patent publication is attached to the support structure via acompressible retaining ring. More particularly, the internal surface ofthe skirt is configured to mate with the outer surface of the supportstructure of the flashlight at select locations to properly position theskirt relative to the face cap and the support structure. Thecompressible retaining ring is then provided in a channel extendingaround the outer surface of the support structure to create aninterference fit with a feature provided on the internal surface of theskirt. Because the skirt must be removable in order for the user toaccess the light source alignment device included in the flashlightdescribed in the '354 publication, however, the compressible retainingring may not provide a permanent type interference fit. Indeed, topermit the average user to remove the skirt without undue effort, theinterference fit must be relatively weak. As a result, the skirt of thisflashlight is subject to being unintentionally disconnected from thesupport structure if the flashlight is dropped on its tail or otherwisereceives a jolt to the tail of the flashlight. The unintentionaldetachment of the skirt from the support structure in this manner isundesirable.

Although the '372 patent and '354 publication indicate that the lightsource employed in the flashlights described in each of the patentdocuments may be an LED, these patent documents do not teach aconfiguration that suitably addresses the thermal management issuescreated by high power, high brightness LEDs.

Some advanced portable lighting devices provide multiple functions fordifferent needs. For example, a power saving mode and/or an SOS mode maybe implemented in a flashlight or other portable lighting devices inaddition to the normal “full power” mode. In such portable lightingdevices, the user typically elects the desired mode of operation bymanipulation of the main power switch. For example, when the flashlightis in the normal mode or the power save mode of operation, theflashlight may be transitioned to another mode of operation, such as anSOS mode by manipulating the main power switch to momentarily turn offand then turn back on the flashlight.

Typically the functionality of multi-mode portable lighting devices ofthis sort is provided by a microcontroller, which remains powered by thebatteries at all times. As a result, the volatile memory of themicrocontroller may be used to remember the current mode of theflashlight, and thus determine which mode to transition into in theevent that a user enters the proper command signal. However, if theportable lighting device—particularly in the case of largerflashlights—is accidentally hit against or dropped on a hard surface,the inertia of the battery or batteries may cause the battery orbatteries to disconnect from one of the battery contacts for a shortperiod of time. This disconnection will also cause a power loss to themicrocontroller, thereby causing the microcontroller to lose track ofthe mode the flashlight or other lighting device was in prior to thepower loss. As a result, the microcontroller will reset the flashlightor other lighting device to its default mode, which is typically off,rather than automatically returning to the prior mode of operation.Resetting under such circumstances is undesirable and potentiallyhazardous.

Portable lighting devices that include advanced functionality typicallyinclude a printed circuit board with a microcontroller or microprocessorto provide the desired functionality. A need exists, however, for a pushbutton switch assembly that includes an integral circuit board that maybe readily employed in a variety of portable lighting devices to providemultiple levels of functionality to the same.

In view of the foregoing, a need exists for an improved technique ofattaching a flashlight skirt to the flashlight while also providing auser friendly operation when detaching the skirt. A separate need alsoexists for an improved portable lighting device that addresses or atleast ameliorates one or more of the problems discussed above.

SUMMARY

It is an object of the present invention to address or at leastameliorate one or more of the problems associated with flashlightsand/or portable lighting devices noted above. Accordingly, in a firstaspect of the invention, a flashlight with a detachable head skirt thatmay be selectively locked to and unlocked from the flashlight via alocking mechanism is provided.

In one embodiment, the locking mechanism comprises a skirt lock ringthat is at least partially interposed between an internally disposedhead member and an externally disposed head skirt. The skirt lock ring,the interior surface of the skirt head, and the exterior surface of thehead member are preferably configured so that the skirt lock ring may berotated between a first position in which the head skirt is at leastaxially locked to the head member and a second position in which thehead skirt is axially unlocked from the head member and may be removedfrom the flashlight.

In another embodiment, the head and switch assembly have a hollow headand a skirt locking ring. The outer surface of the head can have a frontsection, an aft section, and a cylindrical midsection. The cylindricalmidsection can have a plurality of protuberances. Each of theprotuberances can have a cut facing to the front section. Each of theprotuberances can have a lock member formed by an under cut. The innersurface of the skirt lock ring has a front end, an aft end and a middleportion. The middle portion can have a plurality of first indexing bumpsand the aft end can have a plurality of second indexing bumps. Each ofthe first indexing bumps can be aligned to one of the second indexingbumps to form a plurality of channels. Each of the first indexing bumpsand the second indexing bumps can be constructed by two high plateauregions that are separated by one of low plateau region. The skirt lockring can be locked by the head when each of the protuberances is alignedwith a low plateau region.

In yet another embodiment, a head assembly may comprise a head skirthaving an inner surface. The aft section of the head can have an annulargroove sized to receive a portion of a ball. At least one of the highplateau regions of the second indexing bumps can have a hole sized toreceive the ball. The inner surface of the head skirt has a front end.The inner surface of the head skirt has an annular groove near the frontend. The head skirt may be locked to the head when the ball extends intothe annular groove of the head skirt. On the other hand, the head skirtis not locked to the head by the ball when the ball does not extend intothe annular groove.

In yet another embodiment, the number of protuberances can be the sameas the number of channels. In one embodiment, the number ofprotuberances can be six. In one embodiment, the width of a plurality ofprotuberances can be smaller than the width of a plurality of channels.In one embodiment, three of the high plateau regions of the secondindexing bumps has a hole sized to receive the balls, the three holesare placed and separate from each other with equal distance. In oneembodiment, the head assembly may comprise a wave spring for pushing theskirt lock ring to a lock position.

In a second aspect of the invention, a method for mounting a head skirtto a skirt lock ring of a flashlight is provided. In one embodiment, themethod comprises the steps of rotating the skirt lock ring until theskirt lock ring is aligned in a moving position with a head, pushing theskirt lock ring from a moving position to a rotating position, rotatingthe skirt lock ring from a rotating position to a locking position, andreleasing the skirt lock ring to the locking position.

In one embodiment, the head skirt can be locked by the skirt lock ringwhen the skirt lock ring is in the rotating position and the lockingposition.

In a third aspect of the invention, a flashlight with multiple modes ofoperation is provided. The flashlight has a main power source, an userinterface, a microcontroller having an internal memory, and a pluralityof temporary mode memory devices not residing in the microcontroller.The user interface can have an off position, a momentary position, and alatch position. The microcontroller can have a plurality ofbidirectional input/output ports. The plurality of temporary mode memorydevices can be coupled to the plurality of bidirectional input/outputports of the microcontroller. When the user interface is staying in thelatch position for a period of time, the microcontroller can read theprevious mode information from the internal memory, increment the modevalue by one to obtain a current mode information, and write the currentmode information into the mode memory devices. In one embodiment, thetemporary mode memory devices can be constructed by RC circuits.

In a forth aspect of the invention, a flashlight having a reversepolarity protection circuit is provided. The flashlight has a main powersource, a controller, and a power control circuit. The controller canhave an input and an output. The power control circuit can beelectrically coupled to the main power source and the output of thecontroller. The power control circuit can provide a voltage output tothe controller substantially the same as the main power source when thebattery count is below a predetermined value. The power control circuitcan also provide a voltage output to the controller substantially lowerthan the main power source when the battery count is above or equal tothe predetermined value. In one embodiment, the controller is amicrocontroller. In one embodiment, the predetermined value can be four.

In a fifth aspect of the invention, a flashlight having a power profileinformation stored in its memory is provided. The flashlight has a mainpower source, a lamp, a lamp driving circuit for providing power sourceto the lamp, and a microcontroller. The main power source has a limitedlife cycle including a high voltage period, a voltage depletion periodand a low voltage period. The microcontroller has an internal memory forstoring data battery count information. The microcontroller has a lampdrive output pin. The lamp drive output pin can be coupled to the lampdriving circuit. When the main power source is in the high voltageperiod, the microcontroller can provide a high duty cycle signal to thelamp drive output pin for the lamp driving circuit to provide a highduty cycle power supply to the lamp. When the main power source is inthe voltage depletion period, the microcontroller can gradually declinethe duty cycle signal to the lamp drive output pin for the lamp drivingcircuit to provide a gradually declined power supply to the lamp. Whenthe main power source is in the low voltage period, the microcontrollercan provide a low duty cycle signal to the lamp drive output pin for thelamp driving circuit to provide a low duty cycle power supply to thelamp.

In one embodiment, a power profile can be calculated real-time based ona cell count variable stored in a non-volatile memory of themicrocontroller. The microcontroller may store a power profileinformation for the main power source in the internal memory. Themicrocontroller can use the power profile information as an indicationthat in which period the main power source is currently stay. In oneembodiment, the microcontroller can also store a second power profileinformation for a second main power source that can replace the mainpower source. In one embodiment, the high duty cycle is 100%. In oneembodiment, the low duty cycle is 10%. In other embodiments, the lowduty cycle is greater than 10%, but less than 90%.

Further aspects, objects, and desirable features, and advantages of theinvention will be better understood from the following descriptionconsidered in connection with the accompanying drawings in which variousembodiments of the disclosed invention are illustrated by way ofexample. It is to be expressly understood, however, that the drawingsare for the purpose of illustration only and are not intended as adefinition of the limits of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a flashlight according to one embodiment of thepresent invention.

FIG. 2 is a cross-sectional view of the flashlight of FIG. 1 taken alongthe plane indicated by 102-102.

FIG. 3 is an enlarged cross-sectional view of the forward section of theflashlight of FIG. 1 taken through the plane indicated by 102-102.

FIG. 4 is an exploded perspective view of the flashlight of FIG. 1.

FIG. 5A is an enlarged exploded perspective view of a portion of thehead assembly of the flashlight of FIG. 1. FIG. 5B is an enlargedexploded perspective view of the adjustable ball assembly portion of theflashlight of FIG. 1. FIG. 5C is an enlarged exploded perspective viewof the switch assembly portion of the flashlight of FIG. 1.

FIGS. 6A through 6C are different cross-sectional views illustrating onerelative position between the skirt lock ring and head. FIGS. 6D through6F are different cross-sectional views illustrating a second relativeposition between the skirt lock ring and head. FIGS. 6G through 6I aredifferent cross-sectional views illustrating a third relative positionbetween the skirt lock ring and head.

FIG. 7 is a cross-sectional view of a flashlight according to anotherembodiment of the present invention.

FIG. 8 is an exploded perspective view of the adjustable ball assemblyportion of the flashlight of FIG. 7.

FIG. 9 is a circuit diagram illustrating the relationship of theelectronic circuitry according to one embodiment of the invention.

FIGS. 10A-E are schematic circuit diagrams of different components ofthe circuit shown in FIG. 9.

FIGS. 11A-C are diagrams of the power profile for different types ofbatteries.

DETAILED DESCRIPTION

Embodiments of the invention will now be described with reference to thedrawings. To facilitate the description, any reference numeralrepresenting an element in one figure will represent the same element inany other figure. Further, in the description that is to follow, upper,front, forward or forward facing side of a component shall generallymean the orientation or the side of the component facing the directiontoward the front end of the portable lighting device or flashlight.Similarly, lower, aft, back, rearward or rearward facing side of acomponent shall generally mean the orientation or the side of thecomponent facing the direction toward the rear of the portable lightingdevice, (e.g. where the tail cap is located in the case of aflashlight).

Flashlights 100, 300 according to different embodiments of the presentinvention are described in connection with FIGS. 1-11C below. Each ofthe flashlights 100, 300 incorporate a number of distinct aspects of thepresent invention. While these distinct aspects have all beenincorporated into the flashlight 100, 300 in various combinations, it isto be expressly understood that the present invention is not restrictedto flashlights 100, 300 described herein. Rather, the present inventionis directed to each of the inventive features of the flashlights 100,300 described below individually as well as collectively. Further, aswill become apparent to those skilled in the art after reviewing thepresent disclosure, one or more aspects of the present invention mayalso be incorporated into other portable lighting devices, including,for example, head lamps.

Referring to FIGS. 1-2, flashlight 100 includes a barrel 198 enclosed ata rearward end by a tail cap 206 and at a forward end by a head assembly210.

Barrel 198 is preferably made out of aluminum. As is known in the art,barrel 198 may be provided with a textured surface 104 along its axialextent, preferably in the form of machined knurling. A portion offorward end 110 of barrel 198 extends beneath head skirt 194. Acompartment 199 is formed in barrel 198 to hold a portable power source,such as one or more batteries in series, or a battery pack with cellsarranged in series or parallel. Further, the employed batteries orbattery pack may be rechargeable.

Tail cap 206 is also preferably made out of aluminum and is configuredto engage mating threads provided on the interior of barrel 198 as isconventional in the art. However, other suitable means may also beemployed for attaching tail cap 206 to barrel 198. A one-way valve 204,such as a lip seal, may be provided at the interface between tail cap206 and barrel 198 to provide a watertight seal while simultaneouslyallowing overpressure within the flashlight to expel or vent toatmosphere. However, as those skilled in the art will appreciate, otherforms of sealing elements, such as an O-ring, may be used instead ofone-way valve 204 to form a watertight seal. The design and use ofone-way valves in flashlights is more fully described in U.S. Pat. No.5,113,326 to Anthony Maglica, which is hereby incorporated by reference.

If made out of aluminum, the surfaces of barrel 198 and tail cap 206 arepreferably anodized with the exception of those surfaces used to makeelectrical contact with another metal surface for purposes of formingthe electrical circuit of the flashlight. In the present embodiment, anelectrical path is formed between barrel 198 and the case electrode ofthe batteries or battery pack installed in the compartment 199 by spring202 and tail cap 206. In addition to forming part of the electrical pathbetween the barrel and case electrode, spring 202 also urges batteriesor battery pack installed in the compartment 199 forward so that thecenter electrode of the front-most battery or battery pack is urged intoone end of spring contact 174.

Referring to FIGS. 1-4, the present embodiment includes a head 120 towhich a number of other components may be mounted, including, forexample, skirt lock ring 126, wave spring 122, head skirt 194, face cap112, lens 116, and reflector 118 to form a head assembly 210. Head 120,skirt lock ring 126, head skirt 194 and face cap 112 are preferably madefrom anodized aluminum. On the other hand, reflector 118 is preferablymade out of injection molded plastic. The interior surface of reflector118 is preferably metallized to enhance its reflectivity to a suitablelevel.

In the present embodiment, head 120 is a hollow support structurecomprising a front section 216, a midsection 218 and an aft section 230.Head 120 is internally disposed in the present embodiment in that head120 is covered by face cap 112, skirt lock ring 126, and head skirt 194when the flashlight 100 is fully assembled. In other words, in thepresent embodiment, head 120 does not comprise an external portion ofthe flashlight 100. The front section 216 comprises a generallycup-shaped receiving area 232 for receiving reflector 118. Themidsection 218, which extends rearward from the front section 216,includes a generally cylindrical inner surface 234. And, the aft section230, which extends rearward from the midsection 218, includes internalthreads 236 which are configured to mate with external threads 197 onthe forward end of barrel 198. The head 120 is locked to the barrel 198with retainer 132. Retainer 132 is externally threaded with threads 240on its aft end and is outwardly tapered on its forward end. Retainer 132is configured so that external threads 240 mate with internal threads195 provided on the forward end of barrel 198. Because the forward end110 of barrel 198 includes opposing slots 111, when retainer 132 isthreaded into threads 125 of barrel 198, barrel 198 is expanded as thetapered portion of retainer 132 contacts barrel 198 and is then screwedfurther into the barrel 198. When retainer 132 is fully seated in barrel198, head 120 is locked to the barrel 198.

The face cap 112 retains lens 116 and reflector 118 relative to the head120 and reflector 118. In the present embodiment, face cap 112 isconfigured to thread onto external threads 238 provided on the frontsection 216 of the head 120. In other implementations, however, otherforms of attachment may be adopted. An O-ring 114 is provided at theinterface between face cap 112 and lens 116 to provide a watertightseal. As best seen in FIG. 3, reflector 118 is positioned within thecup-shaped receiving area 232 of head 120 so that it is disposed forwardof the head 120 and retainer 132. The internal surface of the cup-shapedreceiving area 232 together with the outer surface of reflector 118 andreflector flange 119 ensure the proper alignment of the principal axisof reflector 118 with the central axis of the barrel 198. The face cap112 in turn clamps O-ring 114, lens 116, and reflector 118 via reflectorflange 119 to head 120.

Head skirt 194 has a diameter greater than that of the barrel 198. Headskirt 194 is also adapted to pass externally over the exterior of thebarrel 198. The forward end 242 of head skirt 194 is configured to matewith the outer surface of a skirt lock ring 126 at select locations toproperly position head skirt 194 relative to face cap 112 and head 120.

The locking mechanism of the head skirt 194 will now be described. FIG.5A shows an exploded view of a portion of head assembly 210. The outersurface of head 120 has a normally smooth surface 266 with an annulargroove 267 on the outer surface of aft section 230 and a plurality ofprotuberances 268 equally spaced from each other around the outercircumference of the midsection 218 of head 120. As best seen in FIGS.6C, 6F, and 6I, a gap 231 is formed between each protuberance 268 andthe front section 216 of head 120. In the present embodiment, sixprotuberances 268 are used. Each of the protuberances 268 has a cut 269on the front end such that each of the protuberances 268 have a reversedL-shaped cross-section in the longitudinal direction of flashlight 100as seen in FIG. 6C, for example. At the toe of the reversed L-shapedprotuberances 268 is a lock member 270. In the present embodiment, thenumber of protuberances 268 is six. In other embodiments, the number ofprotuberances 268 may be different. However, the number of protuberances268 should be an integer number greater than or equal to three.

The inner surface of skirt lock ring 126 has a front end 281, an aft end282 and a middle portion 283 in between. The inner surface of skirt lockring 126 comprises a plurality of longitudinal channels 271 formed by aplurality of first indexing bumps 272 and second indexing bumps 275. Inthe present embodiment, six first indexing bumps 272 are formed near themiddle portion 283 of the inner surface of the skirt lock ring 126 andsix second indexing bumps 275 are formed near the aft end 282 of theinner surface of the skirt lock ring 126. Each of the first indexingbumps 272 comprises two high plateau regions 274 separated by a lowplateau region 273. Similarly, each of the second indexing bumps 275comprises two high plateau regions 277 separated by a low plateau region276. In the present embodiment, some of the high plateau regions 277 ofthe second indexing bumps 275 have a hole 278 sized to receive a ball128. In the present embodiment, three holes 278 are equally spaced fromeach other around the inner circumference of skirt lock ring 126. In thepresent embodiment, the number of first indexing bumps 272 is the sameas the number of second indexing bumps 275. In an alternate embodiment,the number of first indexing bumps 272 may be an integer multiple of thenumber of second indexing bumps 275. In another embodiment, the numberof first indexing bumps 272 is an integer factor of the number of secondindexing bumps 275. In the present embodiment, the number of secondindexing bumps 275 is the same as the number of protuberances 268. Inother embodiments, the number of second indexing bumps 275 may be aninteger multiple of the number of protuberances 268.

FIGS. 6A-C show different cross-sectional views through the head 120 andskirt lock ring 126 when the skirt lock ring 126 has been rotated to aposition which unlocks the head skirt 126 axially from the head 120.FIGS. 6A-6C also show skirt lock ring 126 in a position (position A)relative to head 120 where their aft ends are aligned. Balls 128 nowsits in trench 267 and the top end 279 of ball 128 is lower than the topsurface 280 near the aft end of skirt lock ring 126. Accordingly, headskirt 194 can be freely mounted to or dismounted from skirt lock ring126 at this position. When every protuberance 268 of head 120 is alignedwith a channel 271 of skirt lock ring 126 (as shown in FIG. 6C) byrotating skirt lock ring 126 to a suitable position, then the firstindexing bumps 272 and the second indexing bumps 275 are aligned withthe smooth surface 266 of skirt lock ring 126 (as shown in FIGS. 6A-6B).In this position, skirt lock ring 126 may be freely moved axiallyforward or rearward over head 120. FIG. 6A more particularly shows wherelow plateau regions 273, 276 of skirt lock ring 126 are aligned with thesmooth surface 266 of head 120, and FIG. 6B more particularly showswhere high plateau regions 274, 277 of skirt lock ring 126 are alignedwith the smooth surface 266 of head 120. When the skirt lock ring 126 isindexed to this position, it is in a position in which it may be movedforward or rearward relative to head 120 by an operative amount.However, skirt lock ring 126 can not be rotated relatively to head 120because protuberances 268 and high plateau regions 274 are next to eachother so that high plateau regions 274 extend too far out from skirtlocking ring 126 to pass over protuberances 268.

When skirt lock ring 126 and head 120 are aligned as illustrated inFIGS. 6A-6C, skirt lock ring 126 may be pushed forward to position Bagainst the spring force of wave spring 122, as shown in FIGS. 6D-6F.When skirt lock ring 126 is pushed forward in this manner protuberances268 and high plateau regions 274 are no longer next to each other. As aresult, skirt lock ring 126 can now be rotated relative to head 120because high plateau regions will now pass through gap 231 betweenprotuberance 268 and the front section 216 of head 120 as skirt lockring 126 is rotated. Balls 128, however, no longer sit in trench 267,but instead are disposed on the smooth surface 266. As a result, the topend 279 of ball 128 is now higher than the top surface 280 near the aftend of skirt lock ring 126. If the head skirt 194 is mounted to theskirt lock ring 126, the ball 128 will extend into annular groove 129formed in the interior surface of head skirt 194. However, becauseprotuberances 268 remain aligned with channels 271, the skirt lock ring126 remains subject to being moved rearward to position A shown in FIGS.6A-6C and thus the head skirt 194 is not axially locked to the head 120at this point.

When skirt lock ring 126 and head 120 are aligned as described in FIGS.6D-6F, skirt lock ring 126 can be rotated relatively to head 120. If auser rotates skirt lock ring 126 30° in either direction and thenreleases the skirt lock ring 126 wave spring 122 will bias the skirtlock ring 126 rearward, and the relationship between skirt lock ring 126and head 120 will be the position (position C) as shown in FIGS. 6G-6I.Now, protuberances 268 are aligned with low plateau regions 273 (asshown in FIG. 6I). Further, the spring force of wave spring 122 pushesskirt lock ring 126 rearward until a corner of each low plateau region273 fits into a cut 269 of an opposing protuberance 268 and lock members270 are positioned under the low plateau regions 273. In this manner,skirt lock ring 126 can not be rotated relatively to head 120 becauseeach side of lock member 270 of protuberances 268 is now next to a highplateau region 274. In addition, balls 128 are still disposed on thesmooth surface 266, and, as a result, the top end 279 of ball 128 isstill higher than the top surface 280 near the aft end of skirt lockring 126. Thus, if head skirt 194 is mounted, it will be axially lockedby ball 128 to head 120 and can not be dismounted (as shown in FIGS.2-3).

When head skirt 194 is locked (as shown in FIGS. 2-3), the skirt lockring 126 and head 120 are aligned as illustrated in FIGS. 6G-6I. Toaccess adjusting ring 148 to adjust the alignment of the beam directionof the substantial point source of light, namely LED 145 of LED module144 in the present embodiment, with the principal axis of the reflector,head skirt 194 must be unlocked and slid rearward over barrel 198 atleast far enough for the user to gain access to adjustment ring 148. Theprocedure for accomplishing this is described below.

First, when head skirt 194 is axially locked to the head 120 by theskirt locking ring 126, the skirt lock ring 126 and head 120 are alignedas illustrated in FIGS. 6G-6I. Further, skirt lock ring 126 can not berotated relative to head 120. However, the head skirt 194 is free torotate about the skirt locking ring 126 and barrel 198 to axiallytranslate the light source along the axis of the reflector as discussedmore fully below. Further, the skirt lock ring 126 together with thehead skirt 194 may be pushed forward against wave spring 122 to unlockskirt lock ring 126 from head 120. By rotating the skirt lock ring 12630° in either direction, the skirt lock ring 126 and head 120 arealigned as illustrated in FIGS. 6D-6F, and, as a result, the head skirt194 is axially unlocked from the head member 194 and thus may be removedfrom the flashlight 100. This is because skirt lock ring 126 is now freeto move from position B to position A, and once skirt lock ring 126 andhead 120 are aligned in position A, as shown in FIGS. 6A-6C, balls 128will fall into trench 267 and the top end 279 of balls 128 will nolonger be higher than the top surface 280 near the aft end of skirt lockring 126. Accordingly, head skirt 194 may continue to be moved rearwardand dismounted. is no longer locked by ball 128 and head skirt 194 cannow be dismounted. However, cam 188 will block skirt lock ring 126 frommoving rearward beyond its position in position A.

If it is desired to mount head skirt 194 back to have a completeflashlight assembly, the following procedure can be used. First, headskirt 194 is slid forward over the flashlight barrel 198 until it abutsskirt lock ring 126. Once head skirt 194 abuts skirt lock ring 126, headskirt 194 together with skirt lock ring 126 may be pushed forward toposition B against the spring force of wave spring 122, as shown inFIGS. 6D-6F. Balls 128 are now disposed on the smooth surface 266 andthe top end 279 of ball 128 is higher than the top surface 280 near theaft end of skirt lock ring 126 so as to extend into annular groove 129in head skirt 194.

Once in position B, skirt lock ring 126 may be rotated 30° in eitherdirection and then released. Wave spring 122 will bias the skirt lockring 126 rearward so that the skirt lock ring 126 and head 120 areplaced in position C as shown in FIGS. 6G-6I. At this point, skirt lockring 126 can no longer be rotated because lock members 270 ofprotuberances 268 are now locked by high plateau regions 274. Becauseballs 128 are now disposed on the smooth surface 266, as shown in FIG.6H and skirt lock ring 126 can not be rotated, head skirt 194 is axiallylocked to the head 120 and can not be dismounted (as shown in FIGS.2-3).

Referring back to FIGS. 1-4, an O-ring 124 is provided at the interfacebetween face cap 112 and skirt lock ring 126 to provide a watertightseal.

A one-way valve 130, such as a lip seal, may be provided at theinterface between the head skirt 194 and skirt lock ring 126 to providea watertight seal and to prevent moisture and dirt from entering headand switch assembly 106 between skirt lock ring 126 and the forward end242 of head skirt 194.

As noted above, a portion of the forward end 110 of barrel 198 isdisposed under head skirt 194 when it is mounted to the flashlight 100.The forward most portion of the forward end 110 is interposed between,and threadably attached to, the aft section 230 of the head 120 andretainer 132 as explained above. As a result of the foregoingconstruction, with the exception of the external surface formed byswitch cover 200, all of the external surfaces of the flashlight 100according to the present embodiment may be made out of metal, and morepreferably aluminum.

The forward end 110 of barrel 198 is provided with a hole 244 throughwhich a seal or switch cover 200 extends. The outer surface of forwardend 110 of barrel 198 surrounding switch cover 200 may be beveled tofacilitate tactile operation of flashlight 100. Forward end 110 ofbarrel 198 may also be provided with a groove 246 about itscircumference at a location forward of the trailing edge 248 of headskirt 194 for positioning a sealing element 196, such as an O-ring, toform a watertight seal between the head skirt 194 and barrel 198.Similarly, switch cover 200 is preferably made from molded rubber. Asbest illustrated in FIG. 3, switch cover 200 is preferably configured toprevent moisture and dirt from entering the head and switch assembly 106through hole 244.

Referring to FIG. 5B, the components of an adjustable ball assembly 212according to the present embodiment are illustrated. In the presentembodiment, a lamp or other light source, such as LED 145 of LED module144, is mounted within head and switch assembly 106 so as to extend intoreflector 118 through a central hole provided therein. In particular,LED module 144 is mounted on adjustable ball assembly 212, which in turnis slideably mounted within the forward end 110 of barrel 198. Theadjustable ball assembly 212 is prevented from sliding out of theforward end 110 of barrel 198 by retainer 132, head 120, and camassembly 188, 190 and cam follower assembly 135. In the presentembodiment, cam follower assembly 135 includes a cam follower screw 134,a cam follower roller 136, and a cam follower bushing 138.

An LED module that may be used for LED module 144 is described inco-pending U.S. patent application Ser. No. 12/188,201, filed Aug. 7,2008, by Anthony Maglica et al., the contents of which is herebyincorporated by reference.

Referring to FIGS. 3 and 4, when adjustable ball assembly is positionedinside the front end 110 of barrel 198 and the cam follower assembly 135is positioned in one of the axial slots 111 the radial arms of adjustingring 148 will extend through the opposing slots 110 on the front end 110of barrel 198. Further, the reflector 118 is sized so that the LEDmodule 144 held by the adjustable ball assembly 212 is positionedadjacent the central opening in the aft end of reflector 118.

Still referring to FIG. 3, the moveable cam assembly 188, 190 is sizedto fit around the outer diameter of the barrel 198. Front cam half 188and rear cam half 190 form the cam assembly 188, 190 which is generallya barrel cam with a curved cam channel 250 that extends around the innercircumference of the cam assembly 188, 190. The cam assembly 188, 190 isalso sized such that when installed, the cam follower roller 136 of thecam follower assembly 135 engages with cam channel 250. Accordingly, thecam channel 250 is able to define the axial rise, fall, and dwell of theadjustable ball assembly 212. This is because the cam follower assembly135 is able to slide in the curved cam channel 250 of the cam assembly188, 190 when cam assembly 188, 190 is rotated.

The cam assembly is held longitudinally in place between the aft end ofhead 120 and snap ring 192. Because the curved cam channel 250 isdisposed transverse to the axis of the flashlight 100, when cam assembly188, 190 is rotated, ball housing 140 (along with LED module 144) willmove forwards and backwards along the longitudinal direction offlashlight 100, changing the dispersion of light created by theflashlight from spot to flood and then from flood to spot.

In the present embodiment, forward end 110 of barrel 198 preferablyincludes a groove 252 about its circumference for positioning externalsnap ring 192 to keep the cam assembly 188, 190 from moving toward therear direction of the flashlight 100.

Cam assembly 188, 190 is preferably a two piece construction so that theseparate halves may be fitted over the outer diameter of the flashlightbarrel 198 and the cam follower assembly 135. The tow pieces of themoveable cam assembly 188, 190 may be secured together by any suitablemethod. Preferably, the respective cam halves are formed to snaptogether.

Referring to FIG. 4, longitudinal locking ribs are provided on the outerdiameter of the cam assembly 188, 190. Preferably the locking ribs areequally spaced around the outer circumference of the cam assembly.Corresponding longitudinal locking slots are provided on the interiorsurface of the head skirt 194. As a result, when head skirt 194 ismounted on the flashlight 100 and it is rotated about the axis of thebarrel 198, cam assembly 188, 190 will also be caused to rotate aboutthe barrel 198. Rotation of the cam assembly 188, 190 in turn will causethe adjustable ball assembly 212 to axially displace along the inside ofreflector 118. In this way, the LED module 144 or other light source maybe caused to translate along the reflector axis.

One of the electrode contacts, the positive electrode 254 in the presentembodiment, of LED module 144 extends into a contact disc 146 where theyare preferably frictionally engaged. Another electrode contact, thenegative electrode 256 in the present embodiment, is configured to makeelectrical connection with the inner surface of ball 142, which ispreferably made out of metal. As previously described, the ball 142 isslideably mounted via ball housing 140, which is also preferably madeout of metal, within the front end 110 of barrel 198.

Contact disc 146 is in electrical communication with an outer contactsleeve 158. Outer contact sleeve 158 is slideably engaged with an innercontact sleeve 162. A spring 160 is installed within the outer contactsleeve 158 and the inner contact sleeve 162 to allow relative movementbetween the outer contact sleeve 158 and the inner contact sleeve 162while maintaining electrical communication between contact disc 146 andthe aft end of inner contact sleeve 162. In the present embodiment, theouter contact sleeve 158, inner contact sleeve 162, and spring 160 arepreferably made out of metal.

Outer contact sleeve 158 is further slideably held by a non crush sleeve156, which in turn is held within a retainer 154. Retainer 154 is inturn held by ball housing 140. In the present embodiment, non crushsleeve 156 is preferably made out of metal while retainer 154 ispreferably made out of non-conductive material, such as plastic.

An adjusting ring 148 is located between retainer 154 and contact disk146 to slightly adjust the axial direction of LED module 144, and henceLED 145. Adjusting ring 148 is supported by a push cup 150. Push cup 150is located between the adjusting ring 148 and retainer 154. In thepresent embodiment, a wave spring 152 is further inserted between thepush cup 150 and retainer 154 to provide cushion.

Inner contact sleeve 162 is frictionally held by main switch housing 176so that the aft end of inner contact sleeve 162 is in electricalcommunication with an assembled circuit board 172 at via 258.

Referring to FIGS. 3, 4 and 5C which shows components of a switchassembly 214, switch assembly 214 preferably includes a main switchhousing 176 and a user interface, which is a switch cover 200 in thepresent embodiment. Main switch housing 176 encloses an upper switchhousing 166, an actuator 168, a snap dome 170, an assembled circuitboard 172, a snap in contact 174, a lower switch housing 178, a switchspring 180, a set screw 182, a ground contact 184, and a hex nut 186. Inthe present embodiment, snap in contact 174, switch spring 180, setscrew 182, ground contact 184, and hex nut 186 are preferably made outof metal while main switch housing 176, upper switch housing 166,actuator 168, and lower switch housing 178 are preferably made out ofnon-conductive material, such as plastic.

Referring to FIG. 5C, in the present embodiment, the snap dome 170 hasfour legs with one leg 282 shorter than other three legs 283, 284, 285.The legs 283, 284, 285 are used to contact to ground pads 286, 287, 288on assembled circuit board 172 while the short leg 282 is used tocontact with a momentary pad 289 on assembled circuit board 172. Aring-shaped latch pad 290 is placed in the middle of the assembledcircuit board 172. In the present embodiment, the momentary pad 289 hasa shorter distance from the center of assembled circuit board 172 thanother three pads have.

When switch cover 200 is not depressed, short leg 282 is not in contactwith any portions on assembled circuit board 172. In this situation,both latch pad 290 and momentary pad 289 on assembled circuit board 172are not in contact with ground pads 286, 287, 288 on assembled circuitboard 172.

When switch cover 200 is depressed half way down, actuator 168 pushessnap dome 170 toward assembled circuit board 172. In this situation,Short leg 282 is contacting to momentary pad 289 while the central bodyof snap dome 170 is not contacting with latch pad 290 of assembledcircuit board 172. Since the whole snap dome 170 is made of metal, themomentary pad 289 is now connecting to ground while the latch pad 290 isnot.

When switch cover 200 is further depressed, actuator 168 pushes snapdome 170 further down until snap dome 170 collapse such that the body ofsnap dome 170 is in contact with latch pad 290. Now, not only momentarypad 289 is connecting to ground, latch pad 290 is also connecting toground.

The condition whether momentary pad 289 or latch pad 290 is connectingto ground are received as signals to the assembled circuit board 172,which in turn passes or disrupts the energy flow from the batteries inthe battery compartment 199 to the aft end of inner contact sleeve 162.In this way, head and switch assembly 106 can turn the flashlight 100 onor off. The assembled circuit board 172 may additionally includecircuitry suitable for providing functions to the flashlight 100 whichwill be described in more detail later.

Snap in contact 174 is configured to include curved springs or biasingelements such that the assembled circuit board 172 is protected by thespring force generated by snap in contact 174 from, for example,batteries shifting and pressing on the main switch housing 176. In thisway, an effective electrical connection can be maintained by the biasingelements while protecting sensitive components, such as the assembledcircuit board 172.

Lower switch housing 178 is mounted with two L-shaped contacts 260, 262.L-shaped contact 260 is used to electrically contact with a positivecontact of the assembled circuit board 172 while maintainingelectrically contact with snap in contact 174. L-shaped contact 262 isused to electrically contact with another positive contact of theassembled circuit board 172 while maintaining electrically contact withthe aft end of inner contact sleeve 162. In the present embodiment, oncebatteries are inserted into the battery compartment 199, the centerelectrode of the forward-most battery (not shown) is electricallycoupled to the snap in contact 174, which is electrically coupled to theassembled circuit board 172, which in turn is electrically coupled tothe aft end of inner contact sleeve 162.

Ground contact 184 is secured by hex nut 186 to electrically communicatewith set screw 182, which in turn is electrically coupled to switchspring 180, which in turn is electrically coupled to a ground contact ofthe assembled circuit board 172.

When batteries (not shown) are installed into the battery compartment199, in the present embodiment, an electrical current can flow from thecenter electrode of the forward-most battery to snap in contact 174,L-shaped contact 260, assembled circuit board 172, switch spring 180,set screw 182, barrel 198, tail cap 206, spring 202, and back to thecase electrode of batteries. This electrical path provides electricalpower to the components mounted on the assembled circuit board 172.

Electrical current can also flow from the center electrode of theforward-most battery to snap in contact 174, L-shaped contact 260,assembled circuit board 172, L-shaped contact 262, inner contact sleeve162, spring 160, outer contact sleeve 158, contact disc 146, LED module144, ball 142, ball housing 140, ground contact 184, set screw 182,barrel 198, tail cap 206, spring 202, and back to the case electrode ofbatteries. This electrical path provides electrical power to the LED 145of LED module 144.

Referring to FIG. 7, flashlight 300 has similar construction as that offlashlight 100. The major difference is that, in flashlight 300,incandescent lamp is preferred. Also, a spare lamp holder 208 forholding a spare lamp 209 is inserted in tail cap 206.

FIG. 8 is a partially exploded view of the flashlight of FIG. 7 showingan adjustable ball assembly portion 361 which is corresponding to theadjustable ball assembly portion 212 of flashlight 100 shown in FIG. 5B.According to the embodiment of FIG. 8, flashlight 300 has a ball 342which can hold a contact holder 344. The front end of contact holder 344can receive two conductive pins from a lamp 341. In the presentembodiment, lamp 341 is a incandescent lamp. On the aft end of contactholder 344 is a lamp contact 346 which is integrally molded into contactholder 344 to form an assembly. The contact 346 serves the same functionas the contact disc 146 of flashlight 100 that lamp contact 346 alsoforms a portion of an electric path between batteries (not shown) andlamp 341. Other components of the ball assembly portion 361 are similarto that in flashlight 100 and would not be described further.

Assembled circuit board 172 will now be described. For the purpose ofsimplification, assembled circuit board 172 is described in connectionwith flashlight 100. However, it is understandable that assembledcircuit board 172 is also used in flashlights 300, 400, and 600. FIG. 9is a block diagram illustrating the relationship of the electroniccircuitry of assembled circuit board 172. In the embodiment of FIG. 9,assembled circuit board 172 includes a microcontroller circuit 808, areverse battery protection circuit 802, a linear regulator circuit 804,a first mode memory device 810, a second mode memory device 812, a thirdmode memory device 814, a bypass switch 806, a MOSFET driver 820, a loadswitch 822, a momentary pad 289, a latch pad 288, and a cell count testpoint 824.

Detailed electrical circuit schematics of assembled circuit board 172are shown in FIGS. 10A-E.

FIG. 10A shows a circuit schematic diagram of reverse battery protectioncircuit 802. The reverse battery protection circuit 802 takes thevoltage 702 from the positive electrode of a battery of a battery packand connects it to a source of a p-channel metal-oxide-semiconductorfield-effect transistor (PMOS) 712. The gate of PMOS 712 is connected toground 714 while the drain of PMOS 712 is connected to an internalvoltage supply 704 for assembled circuit board 172. With this reversebattery protection circuit 802, when the battery or battery pack isinstalled in reverse order, no current will be flowed through currentpaths of the flashlights.

Referring to FIG. 10B, microcontroller circuit 808 includes amicrocontroller 720 and connections. Microcontroller 720 receives inputsignals through signal lines ADC_MODE_CAP1 722, ADC_MODE_CAP2 724,ADC_MODE_CAP3 726, MISO 730, MOMENTARY_SWITCH 736, MAIN_SWITCH 738, andRESET 742. Microcontroller 720 also delivers output signals throughsignal lines ADC_MODE_CAP1 722, ADC_MODE_CAP2 724, ADC_MODE_CAP3 726,BYPASS_LDO 734, and LAMP_DRIVE 740. In accordance, signal linesADC_MODE_CAP2 722, ADC_MODE_CAP1 724, ADC_MODE_CAP3 726 arebi-directional. In one embodiment, the microcontroller 720 is acommercial microcontroller having embedded memory, such as, for example,ATtiny24 which is an 8-bit microcontroller manufactured by AtmelCorporation of San Jose, Calif. In another embodiment, themicrocontroller 720 can be a microprocessor. Yet in other embodiments,the microcontroller 720 can be discrete circuits.

Microcontroller 720 has a power supply source 708 to provide voltageinput. Typically, microcontroller 720 can not accept a power supplysource that is higher than a predefined value, for example, 5.5 volts.However, flashlights 100 and 300 can be adjusted to contain two, threeor four batteries (depending on the length of barrel) that the batteryvoltage source 702 (and also 704) can range from 3.0 volts to 6.0 volts.If a flashlight is designed for using four batteries, voltage from thebattery voltage source 702 cannot be used to supply the microcontroller708 directly.

FIG. 10C shows a circuit schematic diagram of linear regulator circuit804. The linear regulator circuit 804 takes the internal voltage supply704 from reverse battery protection circuit 802 as input voltage andconvert it into an digital voltage output source 708 for supplying themicrocontroller 708 through two different paths. The first path isthrough a low drop-out (LDO) linear voltage regulator 716 and the secondpath is to bypass the LDO linear voltage regulator 716 and pass througha PMOS 750.

When flashlight 100 or 300 is designed for receiving four batteries,internal voltage supply 704 can not be used to supply microcontroller720 directly. Signal line BYPASS_LDO 734 would be turned low bymicrocontroller 708. Thus, bipolar transistor 806 with built-inresistors would not be conduct. In accordance, PMOS 750 would not beconduct. Internal voltage supply 704 would be converted to digitalvoltage output source 708 through LDO linear voltage regulator 716 whichwould provide an output voltage source that is lower than the inputvoltage supply. In the present embodiment, the LDO linear voltageregulator 716 would drop the input voltage for about 1.0 volt.

When flashlight 100 or 300 is designed for receiving two or threebatteries, or if flashlights 400, 600 with battery pack are used,internal voltage supply 704 could be used to supply microcontroller 720directly. Signal line BYPASS_LDO 734 could be turned high bymicrocontroller 708. In this situation, bipolar transistor 806 withbuilt-in resistors would be conduct, and therefore, PMOS 750 would beconduct. Internal voltage supply 704 would now be converted to digitalvoltage output source 708 through PMOS 750 and bypass the LDO linearvoltage regulator 716.

In the embodiment of FIG. 10C, internal voltage supply 704 may becoupled to digital voltage source 708 first through a resistor 744before passing through the LDO linear voltage regulator 716 or the PMOS750. Resistor 744 and capacitor 746 constitute a RC filter that filtersout noises, for example, noise due to the switching of PMOS 780 (seeFIG. 10D). This RC filter helps reduce errors when microcontroller 720is making analog-to-digital conversions. In the present embodiment,resistor 744 may be set at 18 Ohms, for example, while capacitor 746 maybe set at 1.0 micro Farad, for example.

Microcontroller 720 can be programmed during manufacturing of flashlightto put the number of battery cell information through cell count testpoint 824 (shown in FIG. 9) to decide whether to turn signal lineBYPASS_LDO 734 high or low. This battery cell count information is alsostored in an embedded non-volatile memory, such as EEPROM, ofmicrocontroller 720 for calculating power profile which will bedescribed in more detail.

FIG. 10D shows a circuit schematic diagram of MOSFET driver circuit 820and a load switch 822. In the embodiment of FIG. 10D, load switch 822 isimplemented by a PMOS 780 that the source of PMOS 780 is coupled tointernal voltage supply 704 while the drain of PMOS 780 is coupled tovoltage output pin 710. Voltage output pin 710 can be coupled to thepositive electrode of the LED 145 of flashlight 100. The gate of PMOS780 is coupled to a MOSFET driver 820, which is implemented by a bipolartransistor 782. The gate of PMOS 780 is also pulled-up to internalvoltage supply 704 by a resistor 778. In accordance, when the base ofbipolar transistor 782 is driven high by signal LAMP_DRIVE 740, bipolartransistor 782 is conduct and so is PMOS 780. Therefore, electric powercan flow from internal voltage supply 704 to voltage output pin 710 toform a portion of a complete loop of electric current path that can turnthe LED 145 on.

In the present embodiments, as long as the batteries or battery pack isinstalled and the connecting parts are working, the assembled circuitboard 172 is supported by power from the batteries or battery packregardless whether the flashlight 100 is switch on or switched off.Microcontroller 720 by default is in a very low power stand-by mode tominimize drain on the batteries. When momentary pad 289 is grounded bysnap dome 170, microcontroller 720 will wake up from low power stand-bymode and turn on a load switch 780, which turns on the LED 145 of theflashlight 100. As long as momentary pad 289 is grounded, the LED 145will be on full power. Once the switch button 200 is released andmomentary pad 289 is no longer grounded, microcontroller 720 will turnoff load switch 780 and the LED 145 will be off. Microcontroller 720will then go back to low power stand-by mode.

If switch button 200 is pressed further that both momentary pad 289latch pad 288 are grounded, the LED 145 will stay on until another fullpress is detected.

Referring to FIG. 10E, the three mode memory devices 810, 812, 814 willnow be described together. The first mode memory device 810 has aninput/output signal line ADC_MODE_CAP1 724 to be coupled tomicrocontroller 720. Signal line ADC_MODE_CAP1 724 is also coupled toone end of resistor 754. The other end of resistor 754 is coupled to aRC circuit with resistor 756 and capacitor 758 connected in parallel.The other end or the RC circuit is coupled to ground. This first modememory device 810 can be used to store information in a temporarymanner. Microcontroller 720 can store an information in mode memorydevice 810 by setting signal line ADC_MODE_CAP1 724 to a high or a low.The high information would be store in the first mode memory device 810for a short period of time, for example, 2 seconds, before it is decayedand cannot be recognized. Microcontroller 720 can execute a readoperation from signal line ADC_MODE_CAP1 724. to retrieve data valuestored in the first mode memory device 810. In the present embodiment,the resistance of resistor 756 is 1.0 Mega Ohms while the capacitance ofcapacitor 758 is 1.0 micro Farad. Similarly, the second mode memorydevice 812 and the third mode memory device 814 can have the sameconfiguration as that of the first mode memory device 810.

In the present embodiments, flashlight 100 have eight modes ofoperation. When the flashlight is switched on, microcontroller 720 readsmode information from an internal memory, for example, an embedded SRAMbuilt in the microcontroller 720. Microcontroller 720 increments themode information by one to obtain a current mode information and storesthe current mode information to the external mode memory devices 810,812, 814. Flashlight 100 goes to the new mode of operation accordingly.

For example, when switch button 200 is hard pressed into latch positionwhile flashlight 100 is in off mode, microcontroller 720 reads theprevious mode information from the embedded SRAM. If the previous modeinformation is 0,0,0, microcontroller 720 increments it by one to obtainthe current mode information, which is 0,0,1. In the present embodiment,a 0,0,1 mode information represent a full power mode. In accordance,flashlight 100 enters the full power mode. Microcontroller 720 thenwrite the current mode information into the three mode memory devices810, 812, 814 by pulling signal lines ADC_MODE_CAP3 726 andADC_MODE_CAP2 722 to low and pulling signal line ADC_MODE_CAP1 724 tohigh.

While the flashlight 100 is in an operation mode other than off mode, ifthe switch button 200 is hard pressed into latch position (bothmomentary pad 289 and latch pad 288 are grounded), and hold it for aperiod of time, for example, two seconds, in the present embodiment,microcontroller 720 interprets that as a command to change mode ofoperation. Microcontroller 720 reads the previous mode information fromthe embedded SRAM and increments it by one to obtain the current modeinformation. If the previous mode information is 0,0,1, for example,then the current mode information would be 0,1,0. Microcontroller 720then writes the current mode information into the three mode memorydevices 810, 812, 814 by pulling signal lines ADC_MODE_CAP3 726 andADC_MODE_CAP1 724 to low and pulling signal line ADC_MODE_CAP2 722 tohigh. In the present embodiment, this 0,1,0 combination represents a 50%power save mode.

In the present embodiment, the 0,1,1 combination stored in the threemode memory devices 810, 812, 814 represents that the current mode is a25% Power Save mode. The rest of the operation modes for flashlight 100are shown in Table 1.

TABLE 1 Operation Modes and Code Mode Name Current mode Next mode Off 0,0, 0 0, 0, 1 Full Power 0, 0, 1 0, 1, 0 50% Power Save 0, 1, 0 0, 1, 125% Power Save 0, 1, 1 1, 0, 0 10% Power Save 1, 0, 0 1, 0, 1 Blink 1,0, 1 1, 1, 0 Beacon 1, 1, 0 1, 1, 1 SOS 1, 1, 1 1, 1, 1

As long as the user continues to hold the switch 200 in the latchposition, the flashlight 100 will make a transition through the lists ofmodes above. Every time a determined period of time, for example, twoseconds, is pass, the mode count will be incremented.

Flashlight 100 may face a power interruption while the flashlight 100 isturned on or turned off. For example, when there is a need for batteryreplacement, flashlight 100 (and also the microcontroller 720) couldexperience a relatively long period of power interruption. When theflashlight is accidentally dropped on the ground or hit to a hardsurface from one end of its ends, the inertia of the batteries orbattery pack could cause the batteries or battery pack to disconnectfrom one of the battery contacts for a short period of time and thatcauses a short period of power interruption.

In the present embodiment, after flashlight 100 has experienced a powerinterruption, no matter it is a relatively long period or a shortperiod, when the power turned back on, microcontroller 720 runs apowered up routine, which includes a read from the three mode memorydevices 810, 812, 814 through signal lines ADC_MODE_CAP3 726,ADC_MODE_CAP2 722, ADC_MODE_CAP1 724. Accordingly, flashlight 100 entersthe mode information indicated by the mode memory devices 810, 812, 814.

For example, after a battery replacement, the mode information indicatedby the mode memory devices 810, 812, 814 should be 0,0,0 since chargesstored on capacitors 758, 764, 770 should have been decade.Microcontroller 720 then reads from the three mode memory devices 810,812, 814 and obtains 0,0,0 as previous mode information. Accordingly,flashlight 100 enters the off mode.

On the other hand, if the flashlight is accidentally dropped on theground or hit to a hard surface from one end of its ends, the inertia ofthe batteries or battery pack could cause the batteries or battery packto disconnect from one of the battery contacts for a short period oftime and that causes a short period of power interruption, typicallyshorter than 0.5 seconds. If the mode of operation right before theaccident is, for example, the SOS mode, the charges stored on capacitors758, 764, 770 are still retained as it is before the accident after thereconnection. Microcontroller 720 then reads from the three mode memorydevices 810, 812, 814 and obtains 1,1,1 as previous mode information.Accordingly, flashlight 100 enters the SOS mode which is the operatingmode before the accident. In other words, the flashlight 100 hasimmunity from such accident.

The power immunity from interruption of flashlight 100 also applies tothe condition when the flashlight 100 is in the off mode. When theflashlight 100 is switched off, microcontroller 720 write 0,0,0 to thethree mode memory devices 810, 812, 814, and microcontroller 720 entersa low power stand-by mode. Therefore, regardless of a short powerinterruption or a long power interruption, after the power connection isrestored, microcontroller 720 reads from the three mode memory devices810, 812, 814 and obtains 0,0,0 as previous mode information.Accordingly, flashlight 100 enters the off mode.

The electronic switch supplies power to LED 145 at different duty cyclesto maximize battery life. Microcontroller 720 including an internalmemory for storing data battery count information and the power profileinformation for a variety of batteries that can be installed toflashlight 100. For most of the battery life, electronic switch 822provides full power (100% duty cycle) to LED 145. As the batteriesdeplete, battery voltage 702 will drop and this is monitored bymicrocontroller 720. Microcontroller 720 uses the power profile for eachbattery to decide when to reduce the duty cycle and when to keep.

Each battery has limited life cycle including a high voltage period, avoltage depletion period and a low voltage period. When battery voltage702 is in the high voltage period, microcontroller 720 provides a highduty cycle signal to the lamp drive output pin 740 for MOSFET driver 820to provide a high duty cycle power supply 710 to LED 145. When batteryvoltage 702 is in the voltage depletion period, the microcontroller 720gradually declines the duty cycle signal to the lamp drive output pin740 for MOSFET driver 820 to provide a gradually declined power supply710 to LED 145. When battery voltage 702 is in the low voltage period,microcontroller 720 provides a low duty cycle signal to the lamp driveoutput pin 740 for MOSFET driver 820 to provide a low duty cycle powersupply 710 to LED 145. FIG. 11A is a power profile for two cellbatteries. FIG. 11B is a power profile for three cell batteries. FIG.11C is a power profile for four cell batteries. By reducing duty cycletowards the end of batteries' life, the usable time of batteries can besignificantly extended.

While various embodiments of an improved flashlight and its respectivecomponents have been presented in the foregoing disclosure, numerousmodifications, alterations, alternate embodiments, and alternatematerials may be contemplated by those skilled in the art and may beutilized in accomplishing the various aspects of the present invention.For example, the power control circuit and short protection circuitdescribed herein may be employed together in a flashlight or may beseparately employed. Further, the short protection circuit may be usedin rechargeable electronic devices other than flashlights. Thus, it isto be clearly understood that this description is made only by way ofexample and not as a limitation on the scope of the invention as claimedbelow.

What is claimed:
 1. A flashlight comprising: a main power source; a userinterface having an off position, a momentary position, and a latchposition; a microcontroller including a plurality of bidirectionalinput/output ports having an internal memory; a plurality of temporarymode memory devices not resident in the microcontroller, the pluralityof temporary mode memory devices being coupled to the plurality ofbidirectional input/output ports of the microcontroller, wherein whenthe user interface remains in the latch position for a period of time,the microcontroller reads the previous mode information from theinternal memory, increments the mode value by one to obtain a currentmode information, and writes the current mode information into the modememory devices.
 2. A flashlight of claim 1, wherein the temporary modememory devices comprise RC circuits.
 3. A flashlight comprising: a mainpower source; a controller having an input and an output; and a powercontrol circuit electrically coupled to the main power source and theoutput of the controller; wherein the power control circuit provides avoltage output to the controller substantially the same as the mainpower source when the battery count is below a predetermined value, andthe power control circuit provides a voltage output to the controllersubstantially lower than the main power source when the battery count isabove or equal to the predetermined value.
 4. A flashlight of claim 3,wherein the controller is a microcontroller.
 5. A flashlight of claim 3,wherein the predetermined value is four.
 6. A flashlight comprising: alamp; a main power source having a limited life cycle, the main powersource providing a power supply in a high voltage range, a middlevoltage range, and a low voltage range during the life cycle, theintersection between the high voltage range and the middle voltage rangebeing a first checking voltage, and the intersection between the middlevoltage range and the low voltage range being a second checking voltage;a lamp driving circuit for transferring the power supply from the mainpower source to the lamp; and a microcontroller including an internalmemory for storing battery count information, the microcontroller havinga lamp drive output pin coupled to the lamp driving circuit, whereinwhen the voltage of the main power source is higher than the firstchecking voltage, the microcontroller provides a high duty cycle signalto the lamp drive output pin for the lamp driving circuit to provide ahigh duty cycle power supply to the lamp, wherein when the voltage ofthe main power source is lower than the first checking voltage andhigher than the second checking voltage, the microcontroller graduallydeclines the duty cycle signal to the lamp drive output pin for the lampdriving circuit to provide gradually declined power supply to the lamp,wherein when the voltage of the main [power source is lower than thesecond checking point, the microcontroller provides a low duty cyclesignal to the lamp drive output pin for the lamp driving circuit toprovide a low duty cycle power supply to the lamp.
 7. A flashlight ofclaim 6, wherein the microcontroller providing a different duty cyclesignal to the lamp drive output pin for the lamp driving circuit toprovide a different duty cycle power supply to the lamp is based on acalculation of a power profile.
 8. A flashlight of claim 7, wherein thecalculation of the power profile is based on a programmable cell countvalue set during the manufacturing of the flashlight.
 9. A flashlight ofclaim 6, wherein the high duty cycle is 100%.
 10. A flashlight of claim6, wherein the low duty cycle is 10%.
 11. A flashlight of claim 6,wherein the low duty cycle is between 10% and 90%.